Partially broken diode???

[Jmillerdoc]

I just finished an 445 build with an Eghemus host and shortly after swapping out a three element for a G-2 lens I noticed when I rotated the laser on axis while pointing it at the wall it dropped in power by about half output...I removed the lens and pointed it at the wall again un-collimated...it does the strangest thing...while pointing at the wall the projection will literally act as if a shade is partially pulled down in front of the aperture and the projection will be cut in half...as I continue to rotate the host on axis the effect disappears....it's as if something inside the diode is loose and either blocking the output or something....it only does it when held in a certain position...also, the overall output is reduced from when it first worked...this occurred immediately after swapping lenses....I looked down into the diode with a magnifying glass and cannot see anything obstructing the aperture....???

Anybody seen something like this before....I am convinced the diode is broken and going to remove it and replace it altogether....just gonna keep this broken one for testing driver loads I guess.

Just curious to see if anyone has had a similar occurrence before and maybe give some insight to what's happened and maybe I can avoid future problems like this...I am pretty sure when I changed the lenses and this began to occur I didn't do anything to damage the diode like screw it down too tight or something...maybe I did..dunno....

 

[123splat]

Try insulating your driver....

 

[jimdt7]

Maybe something has stucked on the lens. Photos would help :beer:

Jim

 

[BShanahan14rulz]

He said that without a lens it behaved the same.

Sounds like something is rolling around in front of the diode window. Or perhaps the diode window itself is broken and moving around?

Also, something as small as a thin strand of wire or hair can show as a huge object blocking the beam, so be very scrupulous when checking for contaminants.

Safety first, remove batteries before attempting to do any cleaning or intense observation.

 

[theman101]

I recently had an 8x 405 that did exactly what you are describing. I think the glass window or something else in the can had broken off and was obstructing the diode. Anyway, don't expect it to last long, mine died just a few minutes of use later

 

[Jmillerdoc]

I think I will attempt to de-can it and see what happens. Never tried before but if I were ever going to this would be the perfect one to practice on....any suggestions on how to de-can a diode? I have some small jewelers files I was going to use to score around the base then try to pry it off with some needlenose plyers...

 

[jimdt7]

^^^ There are some can opening tools.

Jim

 

[BShanahan14rulz]

I think I will attempt to de-can it and see what happens. Never tried before but if I were ever going to this would be the perfect one to practice on....any suggestions on how to de-can a diode? I have some small jewelers files I was going to use to score around the base then try to pry it off with some needlenose plyers...

Yeah, just go around the base of the can with the smallest file you can find, as flush to the gold part as you can go. If you look inside, you can see that you really need to be careful on the top side, but on the bottom side if you go through too far, you'll just hit that mounting peg that the diode die sits on.

I'd just file all the way through in as many points as possible without letting the file get too far into the inside of the can.

 

[123splat]

What a waste of a perfectly good 445.....
It ain't the diode (even though you seem bound and determined to perform an autopsy on it).

 

[sinner]

I am pretty sure it happens when a smoke partice enters into the diode, if you used it without a housing , there is a possibility it can happen.. happened to me with a red diode, open-can.. i pointed it unfocused on the wall and it was good.. i tried to burn some tape unfocused and it did burn a little but afterwards the unfocused beam has a dot near to the middle.. and it had small wavy shadows arround it, like it was coming from the particle that stuck inside the diode.. i tried to magnify it but i couldnt see anything..

 

[BShanahan14rulz]

What a waste of a perfectly good 445.....
It ain't the diode (even though you seem bound and determined to perform an autopsy on it).

I think you should try to clean the window first. pure cotton swabs and 91% isopropyl alcohol should work in a pinch.

If that doesn't at least change things, or if you notice your diode's window is already loose or broken, then you can pick to let it be or decan it. Ultimately, it's your diode, your decision, but I think decanning should be a last resort.

I don't think it's the driver, but photos of the output without a lens would help us figure this out for sure.

 

[bennett326]

guys decanning is a last resort for sure. these 445 diodes are canned for a reason. decanned diodes start to degrade and will die in a few months.

 

[Jmillerdoc]

I have inspected the window very carefully with a high power magnifying glass I have...I assure you there is nothing on the window....it's as if something is lose inside the can and is rolling around inside...as said before, the os a shadow that appears over half the projection when I rotate it on axis at a certain point...when I keep rotating it the shadow will eventually disappear....I wish I had a working camera right now but I don't...

I can also assure you it's not a perfectly good diode anymore...I am pretty sure it's beyond repair. If I open it and learn a little in the process then it was a well spent $45 in my opinion.

Just for the sake of not being stubborn I will try the swab and alcohol...will let you know if it does anything to the output.

My estimation is something broke loose on the inside of the can and is causing this...I could be wrong but that's what it's acting like.

Power supplied to the diode was right at 1700mA, never higher.

I will try to get hold of a camera...I dropped mine a couple of days ago and now it doesn't work either....bummer, not have good luck with my technology lately!

 

[BShanahan14rulz]

Well, the reason I asked for pictures was to make doubly sure that it is actually something physically blocking the output and not just one of the transverse modes disappearing from low current or something. If you can be sure that it is actually something moving in front of the light and not just the same portions of light going dark if/when the voltage hiccups.

Ramping the current on a blue laser diode - YouTube

This video is a good representation of how the electrical input can affect the shape of the output.

 

[Jmillerdoc]

Well, the reason I asked for pictures was to make doubly sure that it is actually something physically blocking the output and not just one of the transverse modes disappearing from low current or something. If you can be sure that it is actually something moving in front of the light and not just the same portions of light going dark if/when the voltage hiccups.

Ramping the current on a blue laser diode - YouTube

This video is a good representation of how the electrical input can affect the shape of the output.

In reference to your video above...if you could imagine that same image, somewhere around the 1.2a point and then rotate the diode to make the image spin on the background....when it spins to let's say 9oclock then almost half of the entire image dissapears....I say almost half because the image is not cut in half at a perfect 90 deg edge but rather about 70 deg angle across the whole image...the right side lit up and the left...dark...nada...dang I wish I had a working camera.....

 

[123splat]

I missed the part about the shadow. I just focused on the "dims when rotated', which is symptomatic of a possible short (mostlikely caused by driver or wire contact with another conductor, like the host wall, another component on the driver, or another wire). Sorry for adding to the confusion.